This lube discussion is getting pretty technical and more difficult to come up with the single best answer. Several things that need consideration: A branded oil like Mobil 1 probably has changed its additive package over the years, especially to comply with new EPA rules. The synthetic base stock probably remained the same. Therefore, what worked well in an engine with a high-lift cam and solid or flat lifters such as we have in our Chrysler 300 letter cars may not work as well now or in the future. Zinc levels do not necessarily tell the whole story (according to the ZDDPlus website, anyway). The P stands for phosphorus and that is the element that is claimed to slowly poison a catalytic converter if it somehow escapes from the crankcase to the exhaust system. Most folks are focused on more zinc, more better, but zinc compounds are used for purposes other than wear protection in oil. The ZDDP compound is apparently generally accepted as the best compound for cam and flat lifter wear protection and it diminishes with miles on each oil change. In quantity, it is probably also reasonably priced. I'm guessing that it might be a patented compound and only produced by one company--either an oil or a chemical company. Each of the oil company gurus that have responded focuses on zinc content of their oil, but at least one guru (Chevron) states his oil has high zinc content and is also compliant with new EPA specs for low or zero phosphorus content. That is possible, but if so, there can be little or none of the needed ZDDP compound in their oil. I have not seen any of the technical responses from any oil company that specifies initial ZDDP content and that is apparently the main issue. It is more likely that the Diesel engine oils contain ZDDP, but as they are also recommended by the oil companies for gasoline engines, I would think they have had to reduce or eliminate the ZDDP compound, also. So, at this time, I recommend sticking with the engine oil you like for your engine and bite the bullet, pay the $2.50/ounce for ZDDPlus and add one ounce per quart of oil at each change. Can't hurt, might help. A little dab will do ya. Cheaper than good whiskey. Correction to previous typo: ZDDPlus retails for $13,440/barrel. C-300'ly, Rich Barber Brentwood, CA 1955 Chrysler C-300 1986 Chrysler LeBaron T&C Convertible with 2.2 Turbo Both cars to receive 10W-30 Pennzoil and a shot of ZDDPlus at next oil change -----Original Message----- From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Jim Maiani Sent: Tuesday, April 29, 2008 6:26 AM To: Chrysler300@xxxxxxxxxxxxxxx Subject: Re: [Chrysler300] Oil talk Hello group. It's poll time... I need your opinions. I've been using Mobil 1 10w30 in my Dart 340 for years. When I changed the oil in my 62 H (413) last week, I used the same Mobil 1 10w30. What is your opinion on using a synthetic oil in our old engines? Should I continue to use it, or drain it and put in mineral? thanks as always for your knowledge. Jim Maiani Houghton Lake Michigan 1962 H 1969 Dodge Dart GTS convertible ----- Original Message ----- From: MRS954@xxxxxxx To: Chrysler300@xxxxxxxxxxxxxxx Sent: Monday, April 28, 2008 2:06 PM Subject: Re: [Chrysler300] Oil talk So, what would be the preferred multi-vis oil for the 413? 15W-40 or 10W-30 ??? Mark -----Original Message----- From: Bob Jasinski <rpjasin@xxxxxxxxxxx> To: Chrysler300@xxxxxxxxxxxxxxx Sent: Mon, 28 Apr 2008 1:43 pm Subject: [Chrysler300] Oil talk I emailed Chevron this morning and got this response, thought the group would benefit. I have been using Delo by Chevron because my local Costco store carries it. It sounds like it has a bit more zinc (1300ppm) than Rotella (1200 ppm). Bob J _____ From: Lube Tek Call Center [mailto:lubetek@xxxxxxxxxxx] Sent: Monday, April 28, 2008 9:33 AM To: Bob Jasinski Subject: RE: Best oil for 1961 Chrysler 300G Thank you for your inquiry. Delo 400 LE 15W40 and 10W30 both have 1300 ppm zinc and meet API classification SM, so they will both give adequate protection for flat tappet cams. _____ From: Bob Jasinski [mailto:rpjasin@xxxxxxxxxxx] Sent: Monday, April 28, 2008 11:53 AM To: Lube Tek Call Center Subject: Best oil for 1961 Chrysler 300G I own a '61 Chrysler 300G with a high performance 413 with 2-4bbl carbs. I am concerned about the reduction in zinc in the new SM motor oils for gas engines. It is my understanding that diesel motor oils have continued to offer higher zinc levels, and I am planning on switching to these types. What is the best Delo oil to use for gas engines? I live in the San Fran bay area and drive the car mostly in the summer and take it to Reno during that time, never in the winter. Discussions on my car club list server are warning users to be aware of the low levels of zinc in SM oils and are recommending adding a product to restore the zinc to the mix, with use of diesel oils a good drop in replacement. Thank you for your knowledgeable response. Bob Jasinski 331 La Questa Dr. Danville, CA 94526 925-831-9727 home 925-366-0035 cell rpjasin@xxxxxxxxxxx [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/Yahoo! 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